TPS can someone explain what i'm looking at

darthcual

Member
Mar 31, 2005
985
19
18
Arlington, TX
I'm chasing a surging idle so decided to check the tps so i took two screws out and took the top off and it appears to be a thumb screw there. What do i do with that? Do i turn it to set idle or what. Sry for the noob question.
 
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darthcual said:
I'm chasing a surging idle so decided to check the tps so i took two screws out and took the top off and it appears to be a thumb screw there. What do i do with that? Do i turn it to set idle or what. Sry for the noob question.
You don't remove the TPS to adjust it. All you need to do is losen the 2 screws so the sensor can move back and forth. Probe the green wire with a DVOM and move the sensor around until you get close to a volt. I did mine yesterday and got it at exactly, .099.

You may also want to clean the IAC valve with some carb cleaner.
 
Turd Furgeson said:
You don't remove the TPS to adjust it. All you need to do is losen the 2 screws so the sensor can move back and forth. Probe the green wire with a DVOM and move the sensor around until you get close to a volt. I did mine yesterday and got it at exactly, .099.

You may also want to clean the IAC valve with some carb cleaner.

IAC is brand new, thanks for the advice need to get my hands on a volt meter.
 
Turd Furgeson said:
You don't remove the TPS to adjust it. All you need to do is losen the 2 screws so the sensor can move back and forth. Probe the green wire with a DVOM and move the sensor around until you get close to a volt. I did mine yesterday and got it at exactly, .099.

You may also want to clean the IAC valve with some carb cleaner.


you mean 0.99v right?
 
Darth,
Don't forget that you may have to ream out the screw holes a tiny bit to allow the sensor to rotate. A dremel tool works real well for this. A small round hand file will also work. A drill is ok, but be careful and not drill the holes too big. The sensor only needs to move a very tiny bit to get big changes. .98 is a good setting. Some older heads will suggest .97 is the max you should go to. Some cars work better at different settings, so you will have to experiment. Probe the green wire with positive lead and the black wire for ground.
Good luck and have fun.
Ken
 
So the car needs to be in the on position but not running correct? I made the mistake of taking it completely off the putting it back on and now my idle is at like 1200rpm. Whoops. I'll need to get my hands on a volt meter b4 i can go any further. This still doesnt fix my problem as i am actually trying to track down a surge (which is still there), but thanks for the advice all.
 
Yes, Key-on, engine off.

An incorrectly set TPS can cause surging for some folks, so do be sure to play around with it and see what happens.

Good luck.
 
Well got it reset to where it was previously but still have the surge. I checked and checked and re-checked for vacuum leaks but found nothing. I wonder if my alternator is the problem? Or perhaps the cap and rotor on the dizzy? *sigh*
 
After rebuilding my motor my tps came out at .88v I had serious idle issues until I set it to .99 It did not solve all the idle problems, but it did have an impact on idle quality.

Other places to get vac leaks...
1) Through the pcv- I currently have too much air being pulled through the crankcase via the filler neck hose/TB. I may have to install a flow restrictor of some sort.

2) Through intake gaskets common to the lifter valley. I had this and boy was it tough to chase that down. Checking crankcase pressure should be done if external vac leaks can't be found. If that pressure turns out to be vac, it will help to narrow down the possibilities.

3) I don't remember who exactly, but several people have found vac leaks in the canister inside the fender (drivers side?). I think this was the a/c & heater vac source?

Hope this can help.
jason